The large number of unknowns could be from an association that didn't get a header response for device type parsing. Also, there's several other columns in the client_first_last table that include the other info in the client detail page, I was just trying to get after the OS type, but if you want device type, there's aruba_device_type, device_type, device_manufacturer, device_model, user_agent_string fields as well. For the 2 device type fields, the aruba_device_type is what the controller parses the client as, while the other field is what AirWave parses the device type as. User agent string is the full response from the device.
You can add the fields into the query and see what output you get. Query might look something like this for example (did not include all fields):
# dbc "select mac, vendor, device_type, device_manufacturer, device_model, device_os, device_os_detail from client_first_last where device_model != '' order by device_os desc, mac asc;"
or you can get the entire table:
# dbc "select * from client_first_last;"